26. NANNOFOSSIL BIOSTRATIGRAPHY, LEG 22, DEEP SEA DRILLING PROJECT
Stefan Gartner, Jr., Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables, Florida
INTRODUCTION The late Neogene zonation Emiliania huxleyi to Discoa- ster quinqueramus is essentially that proposed by Gartner, Calcareous nannofossils were recovered at every site 1969 (see also Gartner, 1973, for a detailed chronology). drilled during Leg 22. Not all sites, however, yielded The remaining Tertiary zones are compiled chiefly from equally good assemblages, and, at some sites only a small Bramlette and Wilcoxon (1967); Hay et al. (1967); Hay and fraction of the interval cored and drilled yielded calcareous Mohler (1967); Gartner (1969; 1971); Martini and Worsley sediments. In general, the most representative calcareous (1970); Martini (1970; 1971); Roth (1970); and Bukry nannofossil successions were recovered at the shallower (1971). Because many of these zones are used in a slightly sites, particularly those along the crest of Ninetyeast Ridge modified sense, a brief characterization is given below for (Sites 214, 216, and 217). Poorest recovery of calcareous all nannofossil zones used in this volume. nannofossils was from the deepest part of the Indian Ocean, in the Wharton Basin east of Ninetyeast Ridge (Sites 211, 212, and 213). This is not surprising as the last three sites Emiliania huxleyi Zone are all well below 5000 meters, and one site (212) is situated well below 6000 meters. This same site did yield The interval of occurrence of Emiliania huxleyi: This zone calcareous sediments over much of the interval cored, but spans somewhat less than 200,000 years. the section is by no means representative. In fact, this site has a most unusual history of carbonate deposition in that Gephyrocapsa Zone all the calcareous sediments seem to have been transported to this site by currents, and probably none were deposited The interval from the last occurrence of Pseudoemiliania as normal pelagic sediments from the water column above. lacunosa to the first occurrence of Emiliania huxleyi. One site west of Ninetyeast Ridge (215) also was more than 5000 meters deep and only part of the section was calcareous. Finally, the site drilled on the Bengal Fan (218) Pseudoemiliania lacunosa Zone yielded calcareous material throughout the interval cored, but because of the large proportion of detrital constituents, The interval from the last occurrence of Discoaster brou- the calcareous nannofossils and other pelagic constituents weri to the last occurrence of Pseudoemiliania lacunosa. were diluted to such an extent in some parts of the interval that they were only rarely encountered. Discoaster brouweri Zone
The interval from the last occurrence of Discoaster surculus NANNOFOSSIL ZONATION to the last occurrence of Discoaster brouweri The top of The calcareous nannofossil zonation used during Leg 22 this zone corresponds very closely to the Pliocene-Pleisto- is indicated below. With the exception of the Discoaster cene boundary as commonly recognized in deep-sea sedi- asymmetricus Zone, all of the zones listed were readily ments. recognized in the sediments recovered in the Indian Ocean. Recognition of the Discoaster asymmetricus Zone depends Discoaster surculus Zone on the identification of Discoaster asymmetricus and Ceratolithus tricorniculatus s.l. in an interval where both The interval from the last occurrence of Reticulofenestra species may be relatively rare, and hence the zone may go pseudoumbilica to the last occurrence of Discoaster undetected in a preliminary examination. Despite this fact, surculus. it has not been excluded from any scheme presented here. Data for constructing the zonal succession and the zonal names are drawn from all available sources. In choosing Reticulofenestra pseudoumbilica Zone from among the various zonations, preference was given to zones which are readily recognized in oceanic as well as in The interval from the last occurrence of nonbirefringent hemipelagic sediments. Provincial species, especially those ceratoliths (chiefly Ceratolithus tricorniculatus and Cerato- restricted to hemipelagic sediments, make poor zonal lithus primus) to the last occurrence of Reticulofenestra markers in oceanic deposits. Notorious among the latter are pseudoumbilica. The top of this zone may be difficult to the mid-Tertiary helicopontosphaeras, pentaliths, holo- determine at times because Reticulofenestra pseudoumbil- coccoliths, Ericsonia subdisticha, and some Miocene astero- ica becomes quite rare and may be represented by only liths (e.g.,Discoaster kugleri). small specimens.
577 S. GARTNER
Discoaster asymmetricus Zone The base of this zone also corresponds closely to the last occurrence of Discoaster neohamatus. The interval from the first occurrence of Discoaster asymmetricus to the last occurrence of nonbirefringent Discoaster neohamatus Zone ceratoliths. Discoaster asymmetricus as well as nonbirefrin- gent ceratoliths may be rare in this interval in some types of The interval from the first occurrence of Discoaster pelagic sediment. Consequently, this zone may be difficult neohamatus to the first occurrence of Ceratolithus tricor- to recognize at times. niculatus. For practical purposes this is a total range zone as the last occurrence of Discoaster neohamatus closely corre- Discoaster mohleri Zone sponds to the first occurrence of the genus Ceratolithus.
The interval from the first occurrence of Discoaster mohleri Discoaster hamatus Zone to the first occurrence of Discoaster multiradiatus. The interval from the first occurrence of Discoaster Heliolithus kleinpelli Zone hamatus to the first occurrence of Discoaster neohamatus.
The interval from the first occurrence of Heliolithus Catinaster coalitus Zone kleinpelli to the first occurrence of Discoaster mohleri. The interval from the first occurrence of Catinaster coalitus Fasciculithus tympaniformis Zone to the first occurrence of Discoaster hamatus.
The interval from the first occurrence of Fasciculithus Discoaster exilis Zone tympaniformis to the first occurrence of Heliolithus klein- pelli. The interval from the last occurrence of Sphenolithus heteromorphus to the first occurrence of Catinaster coali- Cydococcolithina robusta Zone tus. This characterization is a poor one because it relies on the absence of two index species. Cyclicargolithus flo- The interval from the first occurrence of Cydococcolithina ridanus and Cyclolithella nitescens both occur within this robusta to the first occurrence of Fasciculithus tympanifor- zone but do not range to the very top of it. The Discoaster mis. Ellipsolithus macellus and Chiasmolithus bidens first kugleri Zone of other authors corresponds to the top of this occur near the bottom of this zone, and the last-named zone, but as Discoaster kugleri is not a cosmopolitan species species enjoys by far the most cosmopolitan distribution of the zone is not included. the three. Unfortunately, early specimens of this species are frequently identified as Chiasmolithus danicus with the Sphenolithus heteromorphus Zone light microscope. The interval from the last occurrence of Sphenolithus Cruciplacolithus tenuis Zone belemnos to the last occurrence of Sphenolithus hetero- morphus. The Helicopontosphaera ampliaperta Zone of The interval from the first occurrence of Cruciplacolithus other authors corresponds to the lower part of this zone. It tenuis to the first occurrence of Cydococcolithina robusta. is not included here because the marker species, Helicopon- In oceanic calcareous oozes the Tertiary record generally tosphaera ampliaperta, generally is not found in oceanic- does not extend below this level, so that sediments of the type pelagic sediments. Cruciplacolithus tenuis zone are underlain by Upper Creta- ceous deposits. Sphenolithus belemnos Zone
Ceratolithus rugosus Zone The interval of the total range of Sphenolithus belemnos.
The interval from the first occurrence of Ceratolithus Triquetrorhabdulus carinatus Zone rugosus to the first occurrence of Discoaster asymmetricus. The interval from the first occurrence of Triquetrohabdulus Ceratolithus tricorniculatus Zone carinatus to the first occurrence of Sphenolithus belemnos. The species Triquetrorhabdulus carinatus seemingly is The interval from the last occurrence of Discoaster quin- highly susceptible to heavy calcification, which makes queramus to the first occurrence of Ceratolithus rugosus. identification uncertain. Hence, identification of the zone The Miocene-Pliocene boundary falls within this zone. also may be difficult.
Discoaster quinqueramus Zone Sphenolithus ciperoensis Zone
The interval from the first occurrence of nonbirefringent The interval from the first occurrence of Sphenolithus ceratoliths (including but not limited to Ceratolithus ciperoensis to the first occurrence of Triquetrorhabdulus primus) to the last occurrence of Discoaster quinqueramus. carinatus.
578 NANNOFOSSIL BIOSTRATIGRAPHY
Sphenolithus distentus Zone Discoaster diastypus Zone
The interval from the first occurrence of Sphenolithus The interval of the total range of Discoaster diastypus. distentus to the first occurrence of Sphenolithus ciperoensis. Discoaster multiradiatus Zone
Sphenolithus predistentus Zone The interval from the first occurrence of Discoaster multiradiatus to the first occurrence of Discoaster The interval from the last occurrence of Cyclococcolithina diastypus. formosa to the first occurrence of Sphenolithus distentus. Pre-Tertiary sediments recovered during Leg 22 are assignable to the uppermost four Upper Cretaceous nanno- Cyclococcolithina formosa Zone fossil zones which are characterized as follows. The interval from the last occurrence of Discoaster bar- Nephrolithus frequens Zone badiensis to the last occurrence of Cyclococcolithinia formosa. The several zones designated for the lower The interval from the first occurrence of Nephrolithus Oligocene interval, all of which are here included in the frequens to the Cretaceous-Tertiary boundary, which is Cyclococcolithinia formosa Zone, are based on provincial marked by the disappearance of nearly all Upper Creta- specie (e.g., Helicopontosphaera reticulata, Ericsonia sub- ceous species. disticha, Cyclococcolithus margaritae) and are of little or no use in open ocean pelagic sediments. Lithraphidites quadratus Zone
Discoaster barbadiensis Zone The interval from the first occurrence of Lithraphidites quadratus to the first occurrence of Nephrolithus frequens. The interval from the last occurrence of Chiasmolithus grandis to the last occurrence of Discoaster barbadiensis. Tetralithus nitidus trifidus Zone
Chiasmolithus grandis Zone The interval from the first occurrence of Tetralithus nitidus trifidus to the first occurrence of Lithraphidites quadratus. The interval from the first occurrence of Reticulofenestra umbilica to the last occurrence of Chiasmolithus grandis. Eiffellithus augustus Zone Although Reticulofenestra umbilica is a common, dis- tinctive, and cosmopolitan species, the base of this zone The interval from the first occurrence of Broinsonia parca may be difficult to determine at times on the basis of this to the first occurrence of Tetralithus nitidus trifidus. species because it evolved gradually from similar but smaller species. The separation, therefore, becomes subjective. In The nannofossil zonal succession in the Indian Ocean, oceanic sediments the first occurrence of Bramletteius and more specifically, in the equatorial region of the serraculoides closely corresponds to the base of this zone, Ninetyeast Ridge, is very similar to the nannofossil zonal but this form is not common in hemipelagic sediments. succession found by Bukry (1972) for the North Atlantic sediment recovered on DSDP Leg 12. This seems puzzling Nannotetrina alata Zone because the two areas in question, i.e., the northern North Atlantic and the Indian oceans, are separated as much from The interval from the first occurrence of Nannotetrina alata one another as is possible. Moreover, one of the areas is (=Chiphragmalithus quadratus = Chiphragmalithus alatus) tropical and the other is cool temperate to subarctic. It is to the first occurrence of Reticulofenestra umbilica. tempting to smugly point to this similarity of nannofossil zonal successions as proof of the universality of nannofossil Discoaster sublodoensis Zone biostratigraphy, but some of the similarities go beyond that. This is especially true for some Late Cretaceous and The interval from the first occurrence of Discoaster early Tertiary assemblages. The late Maastrichtian index sublodoensis to the first occurrence of Nannotetrina alata. species Nephrolithus frequens is best known from northern Europe. Worsley and Martini (1970) suggest that this Discoaster lodoensis Zone species is a cold water form and, therefore, is absent in low latitude late Maastrichtian sediments. On Leg 22 Nephro- The interval from the last occurrence of Tribrachiatus lithus frequens was recovered on sites very close to the orthostylus to the first occurrence of Discoaster sub- present-day equator, although a Late Cretaceous recon- lodoensis. struction places these same sites at much higher latitudes in the southern hemisphere. Thus, Nephrolithus frequens, like Tribrachiabus orthostylus Zone several modern coccolithophores, probably had a bipolar distribution. The interval from the last occurrence of Discoaster The early Tertiary species, Chiasmolithus danicus, repre- diastypus to the last occurrence of Tribrachiatus sents a similar case. This form has been reported from orthostylus. several localities, but only specimens from northern Europe
579 S. GARTNER
and from the North Atlantic can be assigned to this species unequivocally. In lower Paleocene sediments of the Ninety- east Ridge this species is common, and again the early Tertiary position of the Indian plate has to be invoked to account for the occurrence of this seemingly high latitude form. A bipolar distribution of this species also seems reasonable. Thus, for the Late Cretaceous and early Tertiary the Sample Watznaueria barnesae Cretarhabdus conicus Cretarhabdus crenulatus Tetralithus aeuleus Tetralithus nitidus trifidus Tetralithus quadratus Tetralithus nitidus Broinsonia parca similarity of the zonal succession in the North Atlantic and Arkhangelskiella sp . Micula decussata Indian oceans is not at all unreasonable, especially if it is 211-12-2, 123 cm X X X kept in mind that the Tethyan seaway connected the two 211-12-2, 146 cm X X X X X X X oceans during Cretaceous and early Tertiary time. 211-12-3,25 cm X X X X X X X 211-12, CC X X X RESULTS AND DISCUSSION 211-13-1, 50 cm X X X 211-13-1, 80 cm X X X X X In Figures 1 through 8 are presented checklists of the 211-13-1, 100 cm , X calcareous nannofossils recovered at each of the sites drilled during Leg 22. These checklists have been compiled from 211-13-1, 120 cm X X X X X X shipboard data and from subsequent examinations. The 211-13-1, 140 cm X X latter were directed primarily at determining the limits of 211-13, CC X X X X X occurrence of key index species, so that the biostratigraphic 211-14-1, 58 cm X X X X X framework for each site could be as accurate as possible. The checklists are by no means comprehensive, although Figure 1. Checklist of calcareous nannofossils recovered at they may be considered as representative of the nanno- Site 211. fossils contained in a particular sample. In Figure 9 are summarized the age assignments made on the basis of in, but with a notable lack of sorting of the sediment. Prior calcareous nannofossils of sediments recovered during Leg to that time, redeposition probably was affected chiefly by 22. For additional discussion of the results, the reader is bottom currents which eroded the calcareous sediments referred also to the biostratigraphy section of each site elsewhere and carried them in suspension as a nepheloid report. layer. The short time intervals represented by the consider- Four sites (211, 212, 213, and 215) were located below able thicknesses of calcareous sediments of early middle the present calcium carbonate compensation depth. The Miocene, middle Eocene, and Late Cretaceous age: sorting calcareous sediments recovered at these sites can be of the sediments; and selective solution taken collectively interpreted to be either allochthonous in origin, i.e., they suggest that all these sediments probably were deposited were transported to their present location by currents or below the regional calcium carbonate compensation depth turbidity flows, or, that at certain times the sites were in a local pocket where for some peculiar reason the above the calcium carbonate compensation depth. For Site bottom waters were nearly saturated with calcium 211 an allochthonous origin is suggested by possible current carbonate. bedding of the sediment. On the other hand, deposition Sites 213 and 215 are treated together because their below the lysocline is suggested by the considerable sedimentary history seems very similar even though they solution of most nannofossils, though if the probable Late are on opposite sides of the Ninetyeast Ridge. The upper Cretaceous high latitude location of this site is taken into Miocene to Recent interval is represented by siliceous account, this considerable solution does not necessarily sediments; the lower Eocene to upper Miocene interval by require deposition at great depth. Moreover, the low barren zeolitic clays; and the lower Eocene to basement diversity of the nannofossil assemblage at this site—10 interval is calcareous. At each site the oldest sediment species in an interval that normally yields upward of 50 above basement is Paleocene in age. Towards the top of the species—can be explained, at least partially, by this same calcareous interval, solution effects increase. It seems high latitude location, which is postulated in most Late reasonable that the calcareous sediments at both of these Cretaceous reconstructions of the Indian Ocean. Perhaps a sites were deposited above the calcium carbonate compen- most reasonable explanation for the calcareous nannofossils sation depth, as there is no evidence of slumping or recovered at Site 211 is that they were probably deposited turbidity current deposition. Following the reasoning of at less than abyssal depths in a high latitude sea and may Berger (1972), a likely model is that when the crust at these have been redeposited by current action. two sites was formed, it was at a much shallower depth in For Site 212 the calcareous sediments almost certainly accordance with the crustal elevation-sea-floor spreading have to be allochthonous. Two mechanisms for redeposi- model of Menard (1969) and of Sclater, Anderson, and Bell tion are postulated; turbidity currents probably were the (1971); and only after the crust had moved some distance major transporting agency during the last 12 million years from the spreading center, did it subside below the regional (Cores 1 through 10). This is suggested by a general mixing calcium carbonate compensation depth. If it is assumed of the sediment, so that the major proportion of the fossils that both sites originated at the average ridge crest elevation becomes younger upward in the section, although there is a of 2700 meters and that subsidence occurred at a rate of constant and significant proportion of older fossils mixed 1000 meters during the first 10 m.y. and another 1000
580 a Se 1 1 1 1 1 1 1 s 1 1 J -3 "1 s 1 ç. j 1 1 1 I 1 § 1 § I 1 1 à •l .§ 1 Sample "£. Tetralithus quadratus Discoaslcr suradus Zygodiscus spiralis Ccralolilhus primus (icphymcapsa sp . Sphcnolithus dislmtus Chiasmotithus sp . Discoaslcr hdlus Discoaslcr hrom
Sample Sphenolithus ananhopus Sphenolithus moriformis Sphenolithus radians Fasciculithus tympaniformis | Heliorthus distentus Cambylosphaera dela Chiasmolithus consuetus Chiasmolithus eograndis Chiasmolithus grandis Chiphragmalithus acanthodes | Cyclococcolithina robusta Ellipsolithus macellus Chiasmolithus bidens Chiasmolithus californicus Discoasteroides megastypus Ellipsolithus distichus Discoaster lodoensis Discoaster multiradiatus Discoaster ornatus Discoasteroides kuepperi Discoaster lenticularis Discoaster barbadiensis Discoaster binodosus Discoaster diastypus
213-14-5, 3-4 cm X X 213-14-5, 50-5 lcm X X X X 213-14-5, 100-101 cm X X X 213-14-6, 10-11 cm X X X 213-14-6, 50-51 cm X X X X 213-14-6, 100-101 cm X X X X X X 213-14-6, 140-141 cm X X X X X X X X 213-14. CC X X X X X 213-15-1, 120-121 cm X X X X X X X 213-15-3, 2-3 cm X X X X X X X X X X X 213-15-4, 25-26 cm X X X X X X X X X X X 213-15-4, 70-71 cm X X X X X X X X X 213-15-5, 9-10 cm X X X X X X X X X X X X X 213-15-6, 32-33 cm X X X X X X X X X X X X 213-15. CC X X X X X X X X X 213-16-1, 89-90 cm X X X X X X X X X 213-16-2, 4-5 cm X X X X X X X X X X X 213-16-3, 25-26 cm X X X X X X X X 213-16-4,18-19 cm X X X X X X X X X X X 213-16, CC X X X X X X X X X 213-17-1,120 cm X X X X X X X X
Figure 3. Checklist of calcareous nannofossils recovered at Site 213.
meters during the subsequent 26 m.y. (see Berger, 1972), Sites 214, 216, and 217 were all drilled along the crest the approximate depth of the calcium carbonate compensa- of Ninetyeast Ridge. At all three of these sites presumably a tion level at the time when calcareous sediments ceased to complete section was penetrated, although continuous accumulate at these sites can be roughly estimated. Based coring was done only at Site 214. A nearly complete on paleontological data, calcareous sediments accumulated Tertiary zonal succession can be recognized at Site 214, and at Site 213 for about 8 m.y. after initial formation of the of the two zones not recognized, one, the mid-Pliocene crust and at Site 215 for about 11 m.y. Total sediment Discoaster asymmetricus Zone, frequently is difficult to thickness at the two sites is the same, and it can probably recognize elsewhere in pelagic sections. Moreover, the be assumed, therefore, that the 300-meter difference in missing zone falls between two cores, and it is entirely depth at the two sites reflects original irregularities of ridge possible that the interval containing this zone was lost elevation when they were formed. Thus, Site 215, which during coring. The second zone not recognized at Site 214 accumulated calcareous sediments for about 3 m.y. longer is the mid-Oligocene Sphenolithus predistentus Zone. In than Site 213 started out some 300 meters shallower than this case the missing zone falls within a core, and its the latter site. If an average of 10 m.y. for the calcareous absence either represents a hiatus or inadequate develop- sediment accumulation period at the two sites (a most ment of the Sphenolithus lineage on which is based the convenient figure, indeed) is assumed, then it follows that recognition of this zone. At Site 216, and, to a lesser calcareous sediments ceased to accumulate when these sites extent, Site 217, this zone is developed. Most of the zones dropped to a depth of about 3700 meters. Or, putting it not recognized at Sites 216 and 217 correspond to uncored another way, the regional calcium carbonate compensation intervals or to intervals where recovery was poor. depth was at a depth of about 3700 meters about 40 m.y. At each of the above three sites shoaling can be ago. recognized as basement is approached. It appears that at the It is noteworthy that lower latitude pelagic sediments of time of formation of the crust at these sites, the crest of this same age are characterized by siliceous sediments and Ninetyeast Ridge was at or near sea level. It is of interest, by chert, especially in the Atlantic Ocean, a feature lacking therefore, that members of the family Braarudosphaeradae at Site 213 and developed weakly at Site 215. Although the are sparce in the early Tertiary sediments at Site 214. At above two sites are now in tropical latitudes, a more this site Paleocene and lower Eocene sediments were southerly latitude is implied for these sites in most deposited in what is interpreted to be a lagoonal or reconstructions of the proto-Indian ocean. shelf-like environment. Elsewhere, as in California (Sullivan,
582 NANNOFOSSIL BIO STRATIGRAPHY
1964, 1965), sediments of this age and bathymetric range 110 cm; white chalk fragment covered with fine green contain diverse assemblages of pentaliths, and the same is layer, in brownish-buff chalk true of lower, middle, and upper Eocene sediments else- Micula sp., Watznaueria barnesae, Arkhangelskiella where (Bouché, 1962; Levin and Joerger, 1967; Bramlette cymbiformia, Cylindralithus gallicus, Lithraphidites quad- and Sullivan, 1961; Bybell and Gartner, 1972). It may be ratus, Cretarhabdus sp., Prediscosphaera cretacea, much significant that all of the lower Tertiary nannofloras with unidentifiable debris. Maastrichtian assemblage. diverse pentalith assemblages are from regions which had a subtropical to temperate climate, while all of the Ninety- east Ridge sites, including Site 214, probably originated at relatively higher latitudes or were under the influence of 117 cm; dark layer in brownish-buff chalk high latitude oceanic conditions. Zygodiscus sigmoides, Chiasmolithus danicus, Micula sp., For Sites 216 and 217, no clear ecological inferences can Lithraphidites quadratus, Cruciplacolithus helis, Arkhan- be made from the oldest calcareous nannofossils above gelskiella cymbiformis, Markalius astroporus, Markalius basement. It is unclear whether the low diversity recorded reinhardti, Prediscosphaera cretacea, numerous small, is due entirely to the scarcity of nannofossils in the unidentifiable placoliths. Predominantly Danian assemblage samples, or whether it also is attributable to shallow water with some Maastrichtian contaminants. conditions or high latitude. The nannofossils from Site 218 are precisely what might be expected in an open ocean area that receives a great deal 139 cm; white chalk in mottled interval of clastic sediment. The normal pelagic contribution is Micula sp., Watznaueria barnesae, Lithraphidites quad- diluted by the clastic sediments being transported to the ocean floor by turbid flows and in suspension. Thus the ratus, Arkhangelskiella cymbiforms, Nephrolithus frequens, abundance of nannofossils is related inversely to grain size Cretarhabdus sp., much unidentifiable debris. Late Maas- and directly to carbonate content. In the case of Site 218, trichtian assemblage. sufficient nannofossils were recovered to permit adequate biostratigraphic determinations. The sediments above 103 cm consist largely of unidenti- fiable debris with predominantly Danian age nannofossils admixed with very few Maastrichtian specimens. The matrix and bands below 103 cm have a similar composition CRETACEOUS-TERTIARY BOUNDARY and age. The nannofossils indicate that the Danian age At Sites 216 and 217 on Ninetyeast Ridge the Creta- sediment at this site is not the oldest known Tertiary ceous-Tertiary boundary was penetrated, and at Site 216 although it is early Danian (M.N. Bramlette, personal relatively undisturbed sediment was recovered across this communication). The white chalk fragments below 103 cm boundary (Figure 10). The sediment above about 103 cm is also consist chiefly of unidentifiable debris and contain late uniform in texture, and color changes are gradational. Maastrichtian nannofossil assemblages, including Nephro- Between 103 and 114 cm light buff to white chalk lithus frequens and Cylindralithus gallicus. Thus, on the fragments, mottled and covered with green specks, float in Ninetyeast Ridge, as seemingly everywhere in the marine a matrix of faintly and irregularly banded brownish gray realm, the youngest Cretaceous sediments are separated by chalk. Below about 107 cm the white chalk fragments lack a hiatus from the oldest Tertiary sediments. the green specks, are irregular in size, and flattened Some novel and ingenious explanations have been horizontally. Below 130 cm the dark bands make up an offered for the widespread occurrence of this hiatus. In this even smaller proportion, and the white chalk fragments particular instance the evidence seems to indicate that become more massive. Nannofossil assemblages from a during the interval of nondeposition the chemistry of the selected sample in the vicinity of the Cretaceous-Tertiary ocean water in this region was such as to favor lithification boundary are as follows. of the late Maastrichtian sediments. It is obvious from the 22-216-23-2; 108 cm; brownish-buff chalk sedimentary structures in the core that the Maastrichtian sediments were relatively firm at the time when calcareous Chiasmolithus danicus, Cruciplacolithus helis, Micula sp., sediments again started to accumulate in early Danian time. Makalius reinhardti, Zygodiscus sigmoides, Cribrosphaerella Some solution of Maastrichtian chalk no doubt occurred sp., Markalius astroporus, numerous small and some during the interval represented by the hiatus, but the age of medium-sized placoliths variously assigned to the genera the highest Maastrichtian sediment indicates that relatively Ericsonia, Biscutum, Marlkalius, Coccolithus. Predom- little material was lost. Indeed, most of the hiatus repre- inantly Danian assemblage with some Maastrichtian sents nondeposition rather than solution. According to contaminants. Worsley's (1971) model of the terminal Cretaceous event the relatively short duration of noncarbonate deposition at 109 cm; dark layer in chalk Site 216 would require that the site be located at a Cuiciplacolithus helis, Markalius reinhardti, Zygodiscus relatively shallow depth. This seems to be borne out by the sigmoides, Chiasmolithus danicus, Watznaueria barnesae, late Maastrichtian age of the oldest pelagic sediments above many small unidentifiable placolith as at 108 cm. Predomi- basement recovered at this site and the fact that nantly Danian assemblage with some Maastrichtian immediately above basement the sediment indicates a contaminants. lagoonal or shallow shelf environment.
583 Figure 4. Checklist of calcareous nannofossils recovered at Site 214. Figure 4. (Continued). Figure 4. (Continued). NANNOFOSSIL BIOSTRATIGRAPHY
REFERENCES Hay, W. W. and Mohler, H. P., 1967. Calcareous nanno- plankton from early Tertiary rocks at Pont Labau, Berger, W. H., 1972. Deep sea carbonates: Dissolution France, and Paleocene early Eocene correlations: J. facies and age-depth constancy: Nature, v. 236, p. 392- PaleontoL, v. 41, p. 1505-1541. 395. Hay, W. W., Mohler, H. P., Roth, H. P., Schmidt, R. R., and Bouché, P. M., 1962. Nannofossiles calcaires du Lutetiandu Boudreaux, J. E., 1967. Calcareous nannoplankton bassin de Paris: Rev. Micropaleontologie, v. 5, p. 75-103. zonation of the Cenozoic of the Gulf Coast and Bramlette, M. N. and Sullivan, F. R., 1961. Cocco- Caribbean-Antillean area, and transoceanic correlation: lithophorids and related nannoplankton of the early Gulf Coast Assoc. Geol. Soc. Trans., v. 17, p. 428-480. Tertiary in California: Micropaleontology, v. 7, p. Levin, H. L. and Joerger, A. P., 1967. Calcareous nanno- 129-188. plankton from the Tertiary of Alabama: Micropaleon- Bramlette, M. N., and Wicoxon, J. A., 1967. Middle tertiary tology^. 13, p. 163-182. calcareous nannoplankton of the Cipero section, Martini, E., 1970. Standard Paleogene calcareous nanno- Trinidad W. I.: Tulane Studies Geol., v. 5, p. 93-131. plankton zonation: Nature, v. 226, p. 560-561. Bukry, D., 1971. Cenozoic calcareous nannofossils from the , 1971. Standard Tertiary and Quaternary calcar- Pacific Ocean: San Diego Soc. Nat. Hist. Trans., v. 16, p. eous nannoplankton zonation: Plank. Conf., 2nd, Rome, 303-327. 1970, Proc, p. 739-785. , 1972. Further comments on coccolith stratig- Martini, E. and Worsley, T. T., 1970. Standard Neogene raphy, Leg 12, Deep Sea Drilling Project. In Laughton, calcareous nannoplankton zonation: Nature, v. 225, p. A. S., Berggren, W. A., et al., Initial Reports of the Deep 289-290. Sea Drüüng Project, Volume XII: Washington (U. S. Menard, H. W., 1969. Elevation and subsidence of oceanic Government Printing Office), p. 1071-1083. crust: Earth Planet. Sci. Lett., v. 6, p. 275-284. Bybell, L. and Gartner, S., 1972. Provincialism among Roth, P. H., 1970. Oligocene calcareous nannoplankton mid-Eocene calcareous nannofossils: Micropaleontology, biostratigraphy: Ecolog. Geol. Helv., v. 63, p. 799-881. v. 18, p. 319-336. Sclater, J. G., Anderson, R. N., and Bell, M. L., 1971. The elevation of ridges and the evolution of the Central Gartner, S., 1969. Correlation of Neogene planktonic Eastern Pacific: J. Geophys. Res., v. 76, p. 7888. foraminifer and calcareous nannofossil zones: Gulf Coast Sullivan, F. R., 1964. Lower Tertiary nannoplankton from Assoc. Geol. Soc. Trans., v. 19, p. 585-599. the California Coast Ranges-I Paleocene: Calif. Univ. , 1971. Calcareous nannofossils from the JOIDES Pubs. Geol. Sci., v. 53, p. 163-227. Blake Plateau cores, and revision of Paleogene nanno- , 1965. Lower Tertiary nannoplankton from the fossil zonation: Tulane Studies Geol. PaleontoL, v. 8, p California Coast Ranges—II Eocene: Calif. Univ. Pubs. 101-121. Geol. Sci., v. 53, p. 1-75. Worsley, T. R., 1971. The terminal Cretaceous event: , 1973. Absolute chronology of the Late Neogene Nature, v. 230, p. 318-320. calcareous nannofossil succession in the Equatorial Worsley, T. and Martini, E., 1970. Late Maastrichtian Pacific: Geol. Soc. Am. Bull., v. 84, p. 2021-2034. nannoplankton provinces: Nature, v. 225, p. 1242-1243.
587 S. GARTNER
Sample Toweius sp . Tribrachiatus orthostylus Toweius bisulcus Toweius craticulus Toweius eminens Zygodiscus sigmoides Zygrhablithus bijugatus Chiasmolithus californicus Chiasmolithus consuetus Discoaster ornatus Sphenolithus radians Chiasmolithus bidens Cyclococcolithina robusta Sphenolithus anarrhopus Chiasmolithus eograndis Chiasmolithus grandis Cruciplacolithus tenuis Fasciculithus tympaniformis Heliolithus riedeli Lophodolithus nascens Fasciculithus mitreus Heliolithus kleinpelli Heliolithus concinnus Heliolithus distentus Discoaster diastypus Discoasteroides kuepperi Discoasteroides megastypus Ellipsolithus distichus Ellipsolithus macellus Markalius astroporus Discoaster oraneus Disocaster lodoensis Discoaster mohleri Discoaster multiradiatus Discoaster lenticularis 215-9-3, 130-131 cm X X X X X 215, CC X X X X X 215-10-1, 104-105 cm X X X X X X X X X X X 215-10-2, 30-33 cm X X X X X X X X X X 215-10-3, 42-43 cm X X X X X X X X X 215-10-3, 105-106 cm X X 215-10, CC X X X X X X X X X X X X X X X 215-11-1, 30-31 cm X X X X cf X X X X X X X X X 215-11-2, 4-5 cm X X 215-11-2, 80-81 cm X X 215-11-3, 2-3 cm X 215-11-3, 89-90 cm X X X X X X X X X X 215-11, CC X X X X X X X X X X 215-12-1, 19-20 cm X X X X X X X X 215-12, CC X X X X X X X X X 215-13-2, 4-5 cm X X X X X X X X X X X X X 215-13-2, 97-98 cm X X X X X X X X X X 215-13-3, 90-91 cm X X X X X X X X X 215-13, CC X X X X X X X X X X X 215-14-1, 12-13 cm X X X X X X X X X X 215-14-4, 2-3 cm X X X X X X X 215-14-4, 91-92 cm X X X X X X 215-14-5, 2-3 cm X X X X X X X 215-14-5, 90-91 cm X X X X X X X X 215-14, CC X X X X X X X X 215-15-1, 112-113 cm X X X X X X X 215-15-4, 20-21 cm X X X X X 215-15, CC X X X X X X X X 215-16-1, 99-100 cm X X X X X X X X 215-16-4, 2-3 cm X X X X X X X X 215-16-4, 90-91 cm X X X X X X X X X 215-16, CC X X X X X X X X 215-17-1, 90 cm X X X X X X X X 215-17-1,106 cm X X X X X X 215-17-1, 110 cm X X X X X X X 215-17, CC X X X X
Figure 5. Checklist of calcareous nannofossils recovered at Site 215.
588 NANNOFOSSIL BIOSTRATIGRAPHY
Figure 6. Checklist of calcareous nannofossils recovered at Site 216.
589 S. GARTNER
Figure 6. (Continued).
590 NANNOFOSSIL BIOSTRATIGRAPHY
Figure 6. (Continued).
591 S. GARTNER
Figure 6. (Continued).
592 NANNOFOSSIL BIOSTRATIGRAPHY
Figure 7. Checklist of calcareous nannofossils recovered at Site 217.
593 S. GARTNER
Figure 7. (Continued).
594 NANNOFOSSIL BIOSTRATIGRAPHY
Figure 8. Checklist of calcareous nannofossils recovered at Site 218.
595 Age m. y. Nannofossil Zone 211 212 213 214 215 216 2I6A 217 217A 218
Pleistocene ^^^_ Emiliania luixleyi Zone 1-1 to 1-2 1-1 to 1-3 1-1 1-1 to l.CC "Xs^^^^-v^ Gepliyrocapsa oceanica Zone 1-3 to 1-5 14 lo 1-6 1-2 lo 1-3 2-1 to 4, CC - 5^Λ\Λ\\\^ Pseudoemiliania lacunosa Zone 1-6 to 3-2 ICC 14 to l.CC 5-CC to 8, CC VVvVxV Discoaster brouweri Zone 3-3 to 4-1 \\\\ \. Discoaster surculus Zone 4-2 to 6-3 2-1 to 24 —\ \\\\ Reticulofenestra pseudoumbilica Zone 1-1 64 to8.CC 2-5 to 2, CC Miocene \ \\\ Discoaster asyminetricus Zone 2-1 to 2.CC 11, CC \ \\ Ceratolitluts rugosus Zone 9-1 to9.CC to \ \ Ceratolithus triconüculatus Zone 10-1 to 10-5 \ Discoaster quinqueramus Zone 10-6 to 13-3 3-1 to3,CC 3-1 to 3.CC 12-CC to 15.CC —20- Discoaster neohamatus Zone 10-1 13-5 to 17-1 1-CC to 2,CC 4-1 to 4, CC 16-CC to 23, CC Discoaster hamatus Zone 17-2 to 17-6 4-1 5-1 25, CC \ Catinaster coalitus Zone 17-CC to 18.CC 3,CC to 26, CC \ Discoaster e.xilis Zone 19-1 to 20, CC 4-2 to 4, CC 4,CC 64 \ Splienolithus heteromorplius Zone 10-2 to 15-1 21-1 to 22-1 5-1 5.CC 6-5 to 6-6 \ Splienolithus belenmos Zone 22-2 to 23-2 5-2 to 6,CC 6,CC Oligocene \ Triquetrorliabdiilus rarinatus Zone 23-2 to 24-1 8.CC Splienolithus ciperoensis Zone 24-1 to 25, CC 9-1 to 10, CC 7-1 to 8-1 — 35- Splienolithus distentus Zone 26-1 to 26-6 1 1-1 to 14. CC 8-2 to 9-1 Splienolithus predistentus Zone 15-1 9-2 to "** •-^^ Cyclococcolithina fonnosa Zone 26-CC to 27-6 15-2 to 15-3 9-5 Discoaster barbadiensis Zone 27-CC to 28, CC 15-CC to 17-1 9-6 ^^~ Chiasmolithus grandis Zone 18-2 to 27, CC 29-2 to 31-4 17-2 to 18-1 0-1 to 10, CC Eocene — 45—^^ Nannotetrina alata Zone 31-5 to 32. CC Discoaster sublodoensis Zone 33-1 to 33, CC
' Discoaster lodoensis Zone 34-1 to 35-4 Tribrachiatus orthostylus Zone 14-5 to 14-6 9-3 to9,CC 35. CC Discoaster diastypus Zone 14-6 to 15, CC 10-1 to 11-2 to Discoaster multiradiatus Zone 16-1 to 16. CC 11-3 to 13-2 19-CC to 20-3 12-1 36-2 Discoaster mohleri Zone 17-1 13-3 to 14-4 20-CC to 21, CC Heliolithus kleinpelli Zone 36-4 14-5 to 17-1 22-1 Paleocene -60— Fasciculithus tympaniformis Zone 37-1 17-1 to 17, CC to 12-CC to 14, CC Cvclococcolithina robusta Zone 37-CC to 41, CC 23-2 15-1 Cruciplacolithus helis Zone 15-CC to 16-6 Nephrolithus frequens Zone 29-CCto35,CC 23-3 to 35,CC 16,CCto g Maastrichtian Lithraphidites quadratus Zone 24, CC 8 TI T t V,U VVJ 'CA 7 12-2 to 12, CC 25-1 to 28-6 u U Campanian Eiffellithus augustus Zone 13-1 to 14-2 29-1 to 36 13-1 to 14. CC 3
Figure 9. Summary correlation chart based on calcareous nannofossils of sites drilled on Leg 22, DSDP. NANNOFOSSIL BIOSTRATIGRAPHY 1
1 B m 1 1B •• βI
- I > f N 1 jç i : I1 I 1• 1 1|* 1b? 1
1iv 1• ET IF
'J; i 1 W.
P• 1 t* I j 1
I 1 L I t v .Ni 1
Figure 10. Core photograph across Cretaceous-Tertiary Boun- dary at Site 216, Sample 32-2, 61-150 cm.
597 S. GARTNER
APPENDIX I Discoaster multiradiatus Nannofossil species identified in sediment recovered Discoaster neohamatus during Leg 22 (listed in Alphabetical order). Discoaster neorectus Discoaster ornatus Ahmullerella octoradiata Discoaster pentaradiatus Arkhangelskiella cymbiformis Discoaster quinqueramus Biantholithus sparsus Discoaster saipanensis Biscutum sp. Discoaster sublodoensis Braarudosphaera bigelowi Discoaster surculus Bramletteius serraculoides Discoaster tamalis Broinsonia parca Discoaster tani Cambylosphaera dela Discoaster variabilis decorus Catinaster calyculus Discoaster variabilis pansus Catinaster coalitus Discoasteroides kuepperi Ceratolithus amplificu s Discoasteroides megastypus Ceratolithus cristatus Discolithina japonica Ceratolithus primus Eiffellithus augustus Ceratolithus rugosus Eiffellithus turriseiffeli Ceratolithus tricorniculatus Ellipsolithus distichus Chiasmolithus altus Ellipsolithus macellus Chiasmolithus bidens Emiliania huxleyi Chiasmolithus californicus Chiasmolithus consuetus Fasciculithus Mili Chiasmolithus danicus Fasciculithus mitreus Chiasmolithus eograndis Fasciculithus tympaniformis Chiasmolithus expansus Gephyrocapsa aperta Chiasmolithus gigas Gephyrocapsa caribbeanica Chiasmolithus grandis Gephyrocapsa oceanica Chiasmolithus oamaruensis Chiasmolithus solitus Hayella situliformis Chiasmolithus titus Helicopontosphaera bramlettei Chiastozygus cuneatus Helicopontosphaera compacta Chiphragmalithus acanthodes Helicopontosphaera granulata Coccolithus miopelagicus Helicopontosphaera heezeni Coccolithus pelagicus Helicopontosphaera kamptneri Cretarhabdus conicus Helicopontosphaera recta Cretarhabdus crenulatus Helicopontosphaera wallichi Cretarhabdus decorus Heliolithus kleinpelli Cribrosphaerella ehrenbergi Heliolithus riedeli Cruciplacolithus staurion Heliorthus concinnus Cruciplacolithus tenuis Heliorthus distentus Cyclicargolithus floridanus Heliorthus fallax Cyclicargolithus mansmontium Cyclicargolithus reticulatus Isthmolithus recurvus Cyclococcolithina formosa Kamptnerius magnificus Cyclococcolithina gammation Cyclococcolithina leptopora Leptodiscus larvalis Cyclococcolithina macintyrei Lithraphidites carniolensis Cyclococcolithina robusta Lithraphidites quadratus Cyclolithella nitescens Lophodolithus nescens Cylindralithus gallicus Lucianorhabdus cayeuxi Cylindralithus serratus Markalius astroporus Microhabdulus decoratus Dictiococcites abisectus Micula decussata Discoaster araneus Nannotetrina alata Discoaster asymmetricus Nephrolithus frequens Discoaster barbadiensis Discoaster bellus Oolithotus antillarum Discoaster berggreni Orthorhabdus serratus Discoaster binodosus Peritrachelina sp. Discoaster brouweri Prediscosphaera cretacea Discoaster calculosus Prediscosphaera spinosa Discoaster challengeri Pseudoemiliania lacunosa Discoaster deflandrei Discoaster diastypus Reticulofenestra hillae Discoaster druggi R eticu lofenestra pseudou mb ilica Discoaster exilis Reticulofenestra samodurovi Discoaster hamatus Reticulofenestra scissura Discoaster lenticularis Reticulofenestra umbilica Discoaster lodoensis Rhabdolithina regularis Discoaster loeblichi Rhabdolithina splendens Discoaster mirus Rhabdosphaera claviger Discoaster mohleri Discoaster moorei Scyphosphaera amphora Sphenolithus abies
598 NANNOFOSSIL BIOSTRATIGRAPHY
Sphenolithus anarrhopus Tetralithus quadratus Sphenolithus belemnos Thoracosphaera oblonga Sphenolithus capricornutus Toweis bisulcus Sphenolithus ciperoensis Toweius craticulus Sphenolithus distentus Toweius eminens Sphenolithus furcatolithoides Tribrachiatus orthostylus Sphenolithus heteromorphus Triquetrorhabdulus carinatus Sphenolithus moriformis Triquetrorhabdulus milowi Sphenolithus obtusus Triquetrorhabdulus rugosus Sphenolithus pacificus Sphenolithus predistentus Umbilicosphaera mirabilis Sphenolithus pseudoradians Sphenolithus radians Watznaueria barnesae Sphenolithus spiniger Zygodiscus elegans Tetralithus aculeus Zygodiscus sigmoides Tetralithus mums Zygodiscus spiralis Tetralithus nitidus nitidus Zygrhablithus bijugatus Tetralithus nitidus trifidus Zygrhablithus bijugatus crassus
599